Ideally, the power generated and delivered by electrical utility grid network would have pure sine wave shapes. However, such an idealized electrical utility grid network does not exist. As a result, reinforcing feedback exists where electrical loads draw non-ideal sine waves of current which in turn distorts the shape of the supply voltage waves which further erodes the current wave shape drawn by the loads.
Numerous conventional power quality systems, e.g., uninterruptible power supplies (UPS), power conditioners, active harmonic cancelation systems, harmonic traps, transformer tap chargers, capacitor banks, static VAR compensators, unified power flow controllers, and the like, operate with passive filters, power electronics, and/or a combination of both to improve either the voltage or current waveforms delivered to or from electrical loads. Such conventional power quality systems typically tend to isolate disturbances from the supply voltage or electrical load currents.
Many conventional power quality systems, e.g., tap changers and surge suppressors, have a single function and are designed to improve only one dimension of power quality provided by the electrical utility grid, such as RMS voltage variations or high voltage spikes induced by lightning. Some conventional power quality systems may provide multiple functions in a single device. Examples may include UPSs, Static VAR Compensators, and Unified Power Flow Controllers. Other conventional power quality systems may provide modularity and scalability to allow the systems to scale in size from low to higher power with the same building blocks, e.g., scalable UPSs.
Electrical utility distribution networks often need to scale power processing by functional dimension in addition to just scaling the input to output power capacity rating. For example, often more power processing is needed for voltage regulation than harmonic cancelation or power factor improvement. Thus, electrical utility grids are forced to either purchase multiple single-function power quality system or to purchase a multi-function power quality system that is often oversized for two or more of the required functions. This leads to higher costs for the utility companies and ultimately higher utility bills for consumers. To date, no known conventional power quality system can address such a need faced by electrical utility grids.